We like to use one neutral color in the common living space. This helps each room flow into one another for a more open feel. In rooms that have a door, i.e., office, bathrooms, bedrooms feel free to change up the color. Flat paint helps hide imperfections which is why its general used on ceilings and in apartments. Gloss is most commonly used for doors and trim. On walls we usually recommend a washable matte, satin or eggshell.